One duct detector structure has been disclosed in U.S. Pat. No. 6,124,795 entitled “Detector Interconnect System”, issued Sep. 26, 2000. The '795 patent is assigned to the Assignee hereof and is incorporated herein by reference.
Many of the known duct smoke detectors incorporate a smoke sensor and a power supply board which incorporates power supply circuitry and alarm indicating relays. In such smoke detectors, the smoke sensor unit makes an alarm determination. The circuitry on the power board then receives a signal from the smoke sensor indicating an alarm condition and responds thereto by activating local alarm indicating relays, and/or light emitting diodes to indicate an alarm condition. Such power boards are unable to make decisions based on multiple detected conditions where the unit incorporates more than one smoke sensor. Further, such power boards are unable to signal the condition of the respective sensors to a displaced display/input unit in the absence of extra conductors.
Remote test accessories or devices have been used with duct smoke detectors. Such devices can be mounted on a wall or ceiling and connect to a respective one or more duct smoke detector(s). Such detector(s) might be mounted in an inconvenient location such as in the ceiling of the respective building, or floor of a multi-floor structure. Such devices provide convenient access to an indicator of status of the respective sensor. They can also be used to test and/or reset the respective detector structure.
Known test accessories are usually connected to the respective detector's relay(s) to obtain status signals. Known accessories have been limited to providing status information for only a single sensor. Such accessories often require numerous wires to transfer signals back and forth to/from the respective duct detector.
There continues to be a need for test/display devices or accessories that provide a greater degree of functionality to users than is currently available. It would be desirable to reduce the number of wires needed for communications between the respective duct detector assembly and the respective test/display unit. It would also be desirable to be able to separately test each of several different sensors of the duct detector assembly. It would also be desirable to provide such additional functionality without substantially increasing the manufacturing cost or complexity of such accessories.